/*
 * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
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 *
 *
 *
 *
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 */

package com.sun.jmx.mbeanserver;

import java.lang.ref.WeakReference;
import java.util.WeakHashMap;
import javax.management.Descriptor;
import javax.management.ImmutableDescriptor;
import javax.management.JMX;

public class DescriptorCache {

  private DescriptorCache() {
  }

  static DescriptorCache getInstance() {
    return instance;
  }

  public static DescriptorCache getInstance(JMX proof) {
    if (proof != null) {
      return instance;
    } else {
      return null;
    }
  }

  public ImmutableDescriptor get(ImmutableDescriptor descriptor) {
    WeakReference<ImmutableDescriptor> wr = map.get(descriptor);
    ImmutableDescriptor got = (wr == null) ? null : wr.get();
    if (got != null) {
      return got;
    }
    map.put(descriptor, new WeakReference<ImmutableDescriptor>(descriptor));
    return descriptor;
  }

  public ImmutableDescriptor union(Descriptor... descriptors) {
    return get(ImmutableDescriptor.union(descriptors));
  }

  private final static DescriptorCache instance = new DescriptorCache();
  private final WeakHashMap<ImmutableDescriptor,
      WeakReference<ImmutableDescriptor>>
      map = new WeakHashMap<ImmutableDescriptor,
      WeakReference<ImmutableDescriptor>>();
}
